U.S. Pat. No. 3,680,157, owned by the assignee of this invention, shows a box spring assembly employing metal side, cross, and end rails. The present invention constitutes an improvement on the box spring assembly shown in the aforementioned U.S. Patent.
Wood frame box spring assemblies presently in use generally consist of wooden side and end rails secured together to form a generally rectangular frame, cross rails extending between the side rails, and a plurality of formed wire springs mounted on the frame. Difficulties have in the past been encountered in assembling the individual springs on the frame in which case placement of the springs requires worker decision-making and the design locations are not always achieved. Furthermore, securing metal spring elements to wood, which is often done by stapling, incurs the added risk of failure associated with the use of a non-uniform material (wood). While U.S. Pat. No. 3,680,157 overcomes these disadvantages by employing metal side, end and cross rails, it introduces other difficulties associated with the use of metal. Specifically, the end rails and the cross rails must be welded to the side rails, which increases the complexity and the cost of assembly. Also, an external tacking surface must be provided on the metal frame to which the covering fabric of the box spring assembly can be attached. In normal use, the box spring assembly is supported in a bed either on a conventional wooden bed frame or on a metal angle iron frame to which a headboard can be attached. Metal frame box spring assemblies can produce undesirable noise characteristics when used in connection with metal bed frames, and can cause damage to wooden bed frames under normal load conditions.
It is an object of the present invention, therefore, to provide an improved box spring assembly which attains the objectives of the metal frame box spring assembly while overcoming the disadvantages associated therewith.